ABLATION CATHETER AND ABLATION APPARATUS

Abstract

The present invention relates to an ablation catheter (1) for the ablation of tissues comprising: a telescopic tubular body (4) in turn comprising an external tubular body (4a) and an internal tubular body (4b) concentric with each other, and a rod-like guiding element (5) at least partly housed in the internal tubular body (4b) with at least one free end (5a) protruding from the internal tubular body (4b) in correspondence with a distal end of the telescopic body (4); a positioning head (2, 2″, 2′″, 2°, 2*, 2{circumflex over ( )}) and an ablation head (3) in correspondence with the distal end of the telescopic body (4), the positioning head (2,2″,2″′,2′,2*,2{circumflex over ( )}) being situated in the proximity of the free end (5a) of the rod-like guide, and the ablation head (3) in the proximity of the positioning head (2, 2″, 2″′, 2°, 2*, 2{circumflex over ( )}), in a remote position with respect to the free end (5a); a control handpiece at a proximal end of the telescopic body (4) coupled with the guiding element (5), the ablation head (3), the positioning head (2, 2″, 2′″, 2°, 2*, 2{circumflex over ( )}) and the telescopic tubular body (4); wherein the ablation head (3) comprises at least two ablation elements or petals (3a) that can be moved from a rest position in which they are housed in the external tubular body (4a) and an operating position in which they protrude from the external tubular body (4a) like a petal; wherein each of the ablation elements or petals (3a) comprises: a continuous ablation electrode (3b) which extends without interruption over a circumferential peripheral portion of each petal (3a), substantially along an arc of circumference having a longitudinal axis of the rod-like guiding element (5) as its centre; two side portions (3c) of the petal (3a), each connected to an end of the ablation electrode (3b), in correspondence with a curved section, the side portions (3c) and the ablation electrode (3b) being integral with each other, formed by means of the same folded metallic conductor, each ablation petal (3a) being separate and distinct from another ablation petal (3a) of the ablation head, all the ablation petals (3a) of the ablation head being separately connected to a distinct electric energy generator to cause a radiofrequency ablation and/or a pulsed filed ablation in a powered ablation electrode condition (3b).

Claims

1. A catheter for the ablation of tissues comprising: a telescopic tubular body in turn comprising an external tubular body and an internal tubular body concentric with each other, and a rod-like guiding element at least partly housed in the internal tubular body with at least one free end protruding from the internal tubular body in correspondence with a distal end of the telescopic body; a positioning head and an ablation head in correspondence with the distal end of the telescopic body, the positioning head being situated in the proximity of the free end of the rod-like guide, and the ablation head in the proximity of the positioning head, in a remote position with respect to the free end; a control handpiece at a proximal end of the telescopic body coupled with the guiding element, the ablation head, the positioning head and the telescopic tubular body; wherein the ablation head comprises at least two ablation elements or petals that can be moved from a rest position in which they are housed in the external tubular body and an operating position in which they protrude from the external tubular body like a petal; each of the ablation elements or petals comprising: a continuous ablation electrode which extends without interruption over a circumferential peripheral portion of each petal, substantially along an arc of circumference having a longitudinal axis of the rod-like guiding element as its center; two side portions of the petal, each connected to an end of the ablation electrode, in correspondence with a curved section, characterized in that the side portions and the ablation electrode are integral with each other, formed by means of the same folded metallic conductor, each ablation petal being separate and distinct from another ablation petal of the ablation head, all the ablation petals of the ablation head being separately connected to a distinct electric energy generator to cause a radiofrequency ablation and/or a pulsed field ablation in a powered ablation electrode condition and wherein each ablation petal is produced with a single shape-memory metallic conductor wire having a circular section with a diameter D, and, as L is the linear length of the ablation electrode, there is the following ratio D/L ranging from 0.015 to 0.025.

2. The catheter according to claim 1, wherein said ratio D/L is equal to about 0.02.

3. The catheter according to claim 1, wherein the two side portions of each petal are coated with an electrically insulating material, preferably an insulating paint.

4. The catheter according to claim 1 comprising, for each petal, at least one conductor which extends as far as the handpiece for individually powering each petal, wherein said conductor extends inside the external body, in the space between this and the internal body, preferably arranged spirally.

5. The catheter according to claim 1 comprising, for each petal, at least a first additional conductor at least partly housed in the telescopic tubular body, and destined for preferably extending from the handpiece to the end of the external body.

6. The catheter according to claim 1, wherein each first additional conductor develops spirally inside the external body, and wherein said conductors alternate with at least one additional conductor, inside said external body

7. The catheter according to claim 1, wherein each petal can be moved individually with respect to the others between the rest condition and the extracted, operating condition.

8. The catheter according to claim 1, wherein the ablation petals are rotatingly associated with the telescopic body so that they can be rotated without causing the body and/or the positioning head to also rotate.

9. The catheter according to claim 1, wherein the positioning head comprises at least one extractable positioning arm, said extractable positioning arm being movable between a rest position, in which it is housed in the internal tubular body, and an extracted, operating position, in which it protrudes radially from the internal tubular body.

10. The catheter according to claim 1, wherein the positioning head comprises at least one sensor capable of revealing electric potentials in the tissue and allowing the completeness of the ablation effected, to be revealed.

11. The catheter according to the previous claim 9, wherein said at least one positioning arm is metallic and forms the detection electrode.

12. The catheter according to claim 11, wherein each of said at least one positioning arm is connected to at least one elongated portion which extends as far as the handpiece, housed in the internal body and preferably spiral-shaped.

13. The catheter according to claim 12, wherein second additional conductors are envisaged for the positioning head, which preferably develop spirally and are interspersed with said elongated portions.

14. An apparatus for the ablation of tissues comprising a catheter according to claim 1 and at least one electric energy generator for each petal of said catheter, electrically connected to said petal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The invention is described hereunder with reference to non-limiting examples, provided for illustrative and non-limiting purposes in the enclosed drawings. These drawings illustrate different aspects and embodiments of the present invention and, when appropriate, reference numbers illustrating structures, components, materials and/or similar elements in different figures are indicated with similar reference numbers.

[0077] FIG. 1 illustrates a side view of the distal end of the catheter of the invention in a positioning condition;

[0078] FIG. 2 illustrates a side view of the end of the catheter of FIG. 1 in a functioning condition;

[0079] FIG. 3 illustrates a front view of the catheter of the invention in an insertion condition;

[0080] FIG. 4 illustrates a front view of the catheter of the invention in a positioning condition corresponding to that of FIG. 1;

[0081] FIG. 5 illustrates a front view of the catheter of the invention in a functioning condition corresponding to that of FIG. 2;

[0082] FIGS. 6-10 illustrate side views of variants of a detail of the catheter of the invention;

[0083] FIGS. 11 and 12 illustrate a preferred embodiment of the catheter of the invention, in a side and perspective view;

[0084] FIGS. 13 and 14 illustrate the ablation petals of the catheter of FIGS. 11, 12, in a side and perspective view;

[0085] FIGS. 15 and 16 illustrate the positioning head of the catheter of FIGS. 11, 12, in a side and perspective view;

[0086] FIG. 17 illustrates a section along the plane AA of FIG. 11;

[0087] FIGS. 18 and 19 illustrate sections along the planes AA and BB of FIG. 13;

[0088] FIGS. 20 and 21 illustrate sections along the planes AA, BB and CC of FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

[0089] Whereas the invention can undergo various modifications and alternative constructions, some relative illustrative embodiments are shown in the drawings and are described hereunder in detail.

[0090] It should be understood, however, that there is no intention of limiting the invention to the specific embodiment illustrated but, on the contrary, the invention intends to cover all the modifications, alternative constructions, and equivalents that fall within the scope of the invention as defined in the claims.

[0091] The use of “for example”, “etc.”, “or” indicates non-exclusive alternatives, without limitation, unless otherwise specified. The use of “comprises” means “comprises, but not limited to” unless otherwise specified.

[0092] With reference to the enclosed figures, these show an illustrative but non-limiting embodiment of the catheter of the invention, indicated as a whole with reference 1.

[0093] The catheter 1 comprises a positioning head 2 and an ablation head 3, which will be described in further detail hereunder.

[0094] The catheter 1 also comprises a handpiece in a proximal position, i.e. the control portion that is located outside and can be used for the operator for controlling the action of the catheter itself.

[0095] The control handpiece is positioned at a proximal end of the telescopic body 4 and is operatively connected to the guiding element 5, the ablation head 3, the positioning head 2,2″,2′″,2°,2*,2{circumflex over ( )} and the telescopic tubular body 4 said “operative connection” can be actuated in numerous ways, all known to skilled persons in the field, for example by means of control levers directly or indirectly connected to the above-mentioned parts; consequently no further mention will be made in this respect.

[0096] The form of the handpiece is of no particular interest for the present invention, as it is produced analogously to those known in the art; consequently no further detail is provided herein with respect to the handpiece.

[0097] The catheter 1 comprises a telescopic tubular body 4 in turn comprising: an outer tubular body 4 a, an inner tubular body 4 b, concentric with respect to each other.

[0098] A sheath 4 c, also eccentric with respect to the tubular bodies 4 a, 4 b, is also envisaged for covering the outer tubular body.

[0099] The tubular bodies 4 a and 4 b are preferably cylindrical, even if, in general, they can be oval or polygonal (with rounded corners).

[0100] The catheter 1 also comprises a rod-like guiding element 5 partly housed in the inner tubular body 4 b with a free end 5 a which protrudes from the inner tubular body 4 b.

[0101] The rod-like guiding element 5 is used by the surgeon for guiding the movement of the catheter 1 when inserting it into the patient's veins; this guiding element is per se of the known type and no further mention will be made thereof.

[0102] As can be seen in the figures, the positioning head 2 is situated in the proximity of the free end 5 a of the rod-like guide 5, whereas the ablation head 3 is situated in the proximity of the positioning head 2, but in a remote position with respect to the free end 5 a; in other words, the ablation head 3, when in use, is positioned between the outer tubular body 4 a and the positioning head 2 (see FIG. 2 or 11, 12, for example).

[0103] In general, the ablation head 3 comprises a plurality of ablation elements or petals 3 a.

[0104] In the embodiment illustrated, there are four ablation petals 3 a, but there could also be two, three or more.

[0105] A specific feature of the ablation elements 3 a is that they can be moved, or rather extracted, from a rest position in which they are housed in the outer tubular body 4 a (as in FIGS. 1, 3 and 4) to an operating position in which they protrude from the outer tubular body 4 a extending and broadening out both radially and axially towards the positioning head (as in FIGS. 2, 5, 11-14).

[0106] The movement between the two positions, rest and operating, is effected thanks to a mechanical control positioned in the handpiece of the device and which allows the controlled and adjustable extraction of the ablation petals 3 a.

[0107] In short, between the inner tubular body 4 b and the outer tubular body 4 a, there is at least one housing chamber 6, in which the petals 3 a are positioned in a rest condition and from which they are extracted to be brought into an operating condition.

[0108] In some embodiments, a single housing chamber is envisaged for each petal 3 a, whereas in other embodiments, such as that illustrated, there is only one chamber 6, which in a sectional and front view, is substantially in the form of a circular crown, as it is formed between the outer 4 a and inner 4 b tubular bodies.

[0109] This allows the elements 3 a, when in a rest condition, to be kept withdrawn inside the chamber 6 during the positioning phase of the catheter (see FIGS. 1, 3 and 4), without creating an obstacle during the passage of the catheter inside the patient's veins, and to be extracted from the chamber 6 only when the catheter 1 is positioned.

[0110] At least one, preferably all, of the ablation elements 3 a comprise a continuous (clearly visible in FIG. 5)—or distributed—ablation electrode 3 b which extends without interruption over a circumferential portion, preferably peripheral, of each petal 3 a, substantially along an arc of circumference having a longitudinal axis of the rod-like guiding element 5, as centre.

[0111] In other words, the electrode 3 b occupies the whole of the external body of the petal 3 a, as far as the folded portions with a larger curvature radius which connect it with two side portions 3 c of the petal 3 a, each connected to an end of the ablation electrode (3b).

[0112] Characteristically, the side portions 3 c and the ablation electrode 3 b are integral with each other, produced with the same folded metallic conductor, to which further reference will be made hereunder.

[0113] In short, the petal is composed of a single, folded, solid electric conductor (wire or lamina), of which the circumferential part 3 b forms the actual electrode and the side parts 3 c form side portions of the petal which preferably do not contribute to the ablation process, even if traversed by an electric current.

[0114] This effect is obtained, for example, by coating the side portions 3 c with a layer of electrically insulating material, preferably a paint (not illustrated in the figures).

[0115] Each ablation petal 3 a is separate and distinct from another ablation petal of the ablation head and all the ablation petals 3 a of the head are connected separately to a separate electric energy generator to cause a radiofrequency ablation and/or a pulsed field ablation under a powered condition of the ablation electrode 3 b.

[0116] In this way, the quantity of energy to be supplied in relation to the desired result, can be regulated with extreme precision.

[0117] The electrically conductive material forming the ablation petal 3 a is preferably composed of a shape-memory metallic conductor, even more preferably a Nitinol wire, a material which is known per se for biomedical use; it should be noted that, in general, other metals/metal alloys suitable for the purpose, can also be selected.

[0118] As it is fundamental for the safety and success of the procedure to obtain a clear, continuous, ablation line, without causing surface necrosis and damage to the tissue, ideal conditions for enabling this can be obtained when the petals are of Nitinol, each produced with a single wire having a circular section with a diameter D and with the following ratio between the diameter D and the length L of the active part (circumferential part of the petal, or electrode)

[0119] D/L ranging from 0.015 to 0.025, preferably equal to about 0.02.

[0120] The electrical and mechanical characteristics are therefore optimized in relation to the advantages discussed above.

[0121] It should also be noted that by joining (ideally) the ablation electrodes 3 b, they substantially develop along the same circumference, having the axis of the guiding element 5 as centre; only small arcs of this ideal circumference can remain unjoined (and therefore inactive in the ablation treatment); in this way, during a treatment, an important portion of a blood vessel can be ablated, leaving only small areas of tissue that do not receive direct treatment.

[0122] This can be obtained even more so thanks to the fact that, as the petals 3 a are all produced with the same conductor and with the same dimensions, the elasticity is such that an optimal adherence of the petal to the surface has been observed (the petal under the action of the force against the tissue, becomes elastically deformed until it adheres perfected to the tissue itself, regardless of rhythmic movements of the same) obtaining optimum results in terms of ablation and also in preventing the formation of clots.

[0123] In this sense, thanks to the optimal adherence, a reduced overall quantity of energy can in fact be supplied with respect to cases of the known art, with a consequent lesser heating of the blood possibly in contact with the electrode; at the same time, there is also a lesser heating of the tissue, avoiding necrosis phenomena.

[0124] These small non-treated areas can be subsequently ablated by the surgeon, if necessary, for example by rotating the whole catheter 1 on itself or, more advantageously, only the petals 3 a, keeping the positioning head 2 fixed.

[0125] It should be pointed out that the small angular extension of the arcs in which the ablation electrode 3 b is not active, ensures that the surface treated by each activation of the ablation petals 3 a, is high, much higher than the known radiofrequency catheters with an ablation tip described above.

[0126] This allows a more rapid treatment of the patient, with the advantages indicated above.

[0127] Referring again to the side portions 3 c, with reference to FIG. 2, it can be noted that, in the preferred embodiment illustrated, these do not develop exactly according to a perpendicular axis to that of the guiding element 5 (more specifically, they do not lie on the plane on which the axis of the guiding element 5 is normal): the side portions 3 c are in fact slightly tilted (in a side view) towards the free end 5 a of the guiding element 5, specifically forming a petal.

[0128] The side portions 3 c therefore preferably develop, at least partly, along the generatrices of a cone (or truncated cone, depending on the cases) having as axis the longitudinal axis of the guiding element 5.

[0129] In this way, also due to the intrinsic elasticity of the elements 3 a (whether they be metal laminates or wires), when the ablation segment 3 b is resting on the tissue to be ablated, they are able to dampen, by bending, small oscillations or physiological movements (of both the tissue and surgeon's hand), always keeping the ablation electrode 3 b in contact with the tissue itself, guaranteeing a reliable contact and a consequent effective treatment, with the advantages discussed above.

[0130] For each petal 3 a, one of the side portions 3 c is preferably fixed to the outer tubular body, whereas the other side portion extends (or is connected) as far as the handpiece, where it is connected to the mechanical activation elements or to the specific generator for this.

[0131] Each petal, in addition to being individually activated, can also be individually extracted from the tubular body 4 a in which it is housed in a non-operating condition.

[0132] For this purpose, as can be seen in FIGS. 17, 18, 19, the side portion 3 c of each petal is both mechanically and electrically connected to a specific conductor 39.

[0133] In the preferred embodiment of FIGS. 17, 18, the conductor 39 is integral with the petal 3 a, as it is produced with the same Nitinol wire, with the same diameter.

[0134] In this preferred embodiment, only one side portion 3 c of each petal extends as far as the handpiece, the other portion being fixed in correspondence with the terminal end of the body 4 a, for example a terminal bush; the bush 37 therefore preferably slidingly houses a side portion of each petal 3 c, whereas the other terminal portion of the same petal is fixed to the bush 37 itself.

[0135] In the preferred example of FIGS. 11-21, there are four petals 3 a, therefore eight side portions 3 c and consequently there will be four conductors 39 which extend as far as the handpiece.

[0136] It should be noted that in this preferred embodiment, the conductors 39 of each petal substantially extend as far as the handpiece housed inside the body 4 a, in the space between this and the body 4 b.

[0137] In this route that passes from the petals to the handpiece, the conductors 39 are spirally wound in said space between the bodies 4 a and 4 b.

[0138] Each conductor 39 is electrically isolated from the other so that the powering of one of these does not cause the powering of those nearby.

[0139] Again, with brief reference to the ablation electrodes 3 b, in a particularly advantageous embodiment, they can be selectively activated: in short, each segment 3 b and/or each element 3 a is connected to a power source separately from the others and can be activated individually; for this purpose, the ablation apparatus of the invention comprises a number of radiofrequency electric energy generators equal to that of the petals, which are connected separated and individually to each generator by means of the conductors 39.

[0140] Each electrode 3 b and/or each petal 3 a is therefore connected individually to and can be powered individually by an electric energy source (preferably a radiofrequency generator).

[0141] The surgeon can therefore choose which electrodes 3 b and/or petals 3 a to activate depending on the treatment conditions, and can also repeat it only in correspondence with areas that have not been sufficiently treated and/or avoid activating areas of risk for the patient.

[0142] In a particularly advanced embodiment, each petal 3 a can be advantageously moved individually (with respect to the others) between the rest condition and the, extracted, operating condition.

[0143] This allows the surgeon to extract only the ablation petals 3 a that are necessary, for example when the dimensions/forms of the tissue to be ablated have physiological features that make it advisable.

[0144] The ablation petals 3 a are optionally rotatingly associated with the telescopic body 4 so that they can be rotated without causing the body 4 and/or the positioning head 2 to also rotate; this is obtained, for example in the case of the embodiment of FIGS. 11-21, making the terminal bush 37 (provided with seats in which the conductors 39 pass axially before being connected to the portions 3 c) rotate freely with respect to the body 4 a.

[0145] The petals 3 a are preferably controlled by the handpiece of the device, by means of a mechanical, or electric or pneumatic control.

[0146] This allows a high flexibility of use to be obtained together with a considerable precision: when the surgeon has positioned the catheter 1 in an operating position, he keeps it in the correct position thanks to the positioning head 2 (to which further reference will be made hereunder), and can proceed with treating the various parts of tissue, extracting, rotating and activating the petals 3 a alone, without having to repeat the positioning phase each time.

[0147] This contributes, inter alia, to making the treatment even more rapid, with the advantages indicated above.

[0148] According to an optional and advantageous characteristic, also regardless of the other features of the invention, at least one—preferably a plurality—of additional conductors 38 is envisaged, partly housed in the telescopic tubular body 4, shown in the preferred embodiment of FIGS. 11-21.

[0149] The additional conductors 38 are also housed in the body 4 a, in the space between this and the body 4 b, adjacent to the conductors 39, in particular spirally arranged and interspersed with the latter.

[0150] Said additional conductors 38 are not in electric contact with the petals 3 a and serve to reduce the eddy currents and allow a better control of the energy supplied to each petal during the operating phase of the catheter.

[0151] These advantages are more strongly felt when ablation petals such as those described above are used, which are connected independently to the generators; in this way, eddy currents can be avoided, which could make the treatment less precise.

[0152] This advantage is offered when the ablation apparatus comprises discretized electrodes and also when the electrodes are continuous, as in the catheter described above.

[0153] Eddy currents are generated on the electrodes that are not fed due to those that are being fed at the same time by the respective generator and also cause the powering of the electrodes which, on the other hand, should not be fed.

[0154] The additional conductors 39 are preferably completely contained in the telescopic tubular body 4 and exit from this only on the side of the handpiece.

[0155] Each additional conductor is preferably “U”-folded inside the body, with the two free ends exiting from the proximal side and the folded part which extends into the tubular body as far as its end; alternatively and preferably, all or only part of the additional conductors can be electrically connected to each other.

[0156] The additional conductors 39 are preferably copper wires.

[0157] When the supply conductors of the electrodes are spirally wound in the body 4, the additional conductors 38 are interposed between them, so that each supply conductor 39 of a petal is adjacent, on the two opposite sides, to two branches of the same—or different—additional conductors 38.

[0158] This arrangement, shown in detail in FIGS. 17, 18, 19 allows the phenomenon of eddy currents described above to be completely or almost completely eliminated, so that the ablation treatment can be controlled with extreme accuracy.

[0159] Finally, according to another optional and advantageous feature, the ablation head 3 comprises at least one contact sensor, capable of measuring the contact with the surface to be treated, effecting the treatment with greater precision.

[0160] In particular, in one embodiment, said contact sensor is a capacitive sensor, which indirectly measures the percentage of the electrode 3b which is in contact with the tissue.

[0161] If the ablation is obtained by means of RadioFrequency (RF), for example, the same electrode 3b acts as electrode of the capacitive sensor: by passing a control current, it is in fact possible to reveal whether the same is or is not in contact with the tissue.

[0162] With respect now to the positioning head 2, this comprises a plurality of extractable positioning arms 2 a.

[0163] Said arms 2c pass from a rest position, in which they are housed in the inner tubular body 4b, to an extracted, operating, position, in which they protrude radially from this.

[0164] Also in this case, analogously to the ablation head 3, the extractable positioning arms 2 a remain withdrawn during the insertion phase of the catheter into the vein, until this has reached the area to be treated, so as not to represent an obstacle during this phase, and they are extracted to maintain the position reached, buffered against the walls of the vein/artery to be treated.

[0165] In particular, the extractable arms 2 a are preferably housed between the inner tubular body 4b and the rod-like guiding element 5.

[0166] The extractable arms 2 a form a kind of positioning cage, destined for abutting inside the vein, so as to keep the ablation head correctly in position in correspondence with the ostium of the vein itself.

[0167] In the embodiment illustrated, there are advantageously eight extractable positioning arms 2 a, but, more generically, there could be two, three, four or more.

[0168] Also in this case, the extractable positioning arms 2 a are controlled, in the extraction/re-insertion movement (from the rest position to the operating position and vice versa) by means of a mechanical system situated in the handpiece of the device and which allows the controlled and adjustable exiting of the extractable elements 2 a.

[0169] In other embodiments, the positioning head is an inflatable body (not shown) which is expanded from the rest position to the operating position, like a balloon.

[0170] Also in this case, the inflatable body is preferably housed, under rest conditions, inside the tubular body 4.

[0171] The advantages of using a positioning head 2 provided with arms 2 a, with respect to the inflatable body, are, first of all linked to the fact that the former solution does not block the passage of blood in the vein, as would be the case, on the contrary, with a balloon inflated internally (possibly causing clots or pulmonary hypertension phenomena).

[0172] The inflatable body, moreover, has the advantage of being able to be filled with radio-opaque fluid for a better and more precise visualization.

[0173] According to a particularly advantageous characteristic, regardless of its practical embodiment, the positioning head 2 comprises at least one sensor capable of revealing electric potentials in the tissue, consequently allowing the completeness of the ablation effected, to be revealed.

[0174] This sensor, can be produced in various ways, according to the case.

[0175] It can, for example, be an electrode applied to the arms 2 a or to the inflatable body.

[0176] Alternatively, when the positioning head 2 comprises metal arms 2 a, these, in practice, form the electrode for the detection, thanks to which the electric potentials of the vein are revealed and the isolation of the vein is verified during and at the end of the treatment.

[0177] As far as the positioning head 2 described above, is concerned, it is interesting to note how this comprises, in both the embodiment described above and also in its variants 2″, 2′″, 2°, 2{circumflex over ( )}, Z which will be briefly described hereunder, at least one extractable positioning arm 2 a (and 2 a″, 2 a″′, 2 a°, 2 a*, 2 a{circumflex over ( )} in the variants described hereunder) that can be moved between a rest position, in which it adheres to the rod-like guiding element 5 and is housed in the body 4 of the catheter, and an enlarged operating position, in which it protrudes from the rod-like guiding element 5, broadening out in a radial direction.

[0178] The guiding rod-like element 5 slides in the inner tubular body 4b; the positioning head 2, 2″, 2′″, 2°, 2*, 2{circumflex over ( )}under rest conditions, has such dimensions that it can be inserted in the inner tubular body 4b.

[0179] The catheter 1 can then be inserted into the vein so as to occupy a minimum space and there are no protrusions which could obstruct its passage in the patient's body, subsequently, when the catheter 1 is in the area to be treated, the rod-like element 5 is extracted from the inner tubular body 4b and, when the catheter has reached a correct position, in which it must be fixed, the positioning head 2, 2″, 2″′, 2°, 2*, 2{circumflex over ( )}, is enlarged or, rather, its arms 2 a, 2 a″, 2 a″′, 2 a°, 2 a*, 2 a{circumflex over ( )} are enlarged, which pass from a rest position to an enlarged position and can be abutted against the surrounding tissues, so as to keep the catheter 1 in position.

[0180] The synergy of advantages deriving from the combined use of an ablation head 3 and a positioning head 2, according to the invention, are therefore evident.

[0181] With respect to the description of the alternative forms of the positioning head, reference should be made to FIGS. 6 to 10.

[0182] In the figures, the catheter 1 is shown with the ablation head in a rest condition and, for the sake of clarity, only the positioning head is illustrated.

[0183] In this respect, it should be noted that, in order to avoid encumbering the present description, no further mention is made hereunder of the elements and characteristics in common with the head 2 and arms 2 a, already presented above; it should also be noted that the same parts illustrated in the previous figures are indicated with the same reference numbers.

[0184] FIG. 6 shows a positioning head 2″ in an enlarged condition, which comprises only one arm 2 a″, in the form of a spiral which develops around the rod-like element 5.

[0185] When in an extracted condition, the arm 2 a″ rests with its coils on the tissue, helping to keep the catheter 1 in position.

[0186] FIGS. 7, 8, 9 and 10 show, in an enlarged condition, the positioning heads 2′″, 2°, 2* and 2{circumflex over ( )}each comprising arms 2 a′″, 2 a°, 2 a* and 2 a{circumflex over ( )}which extend according to different geometries around the rod-like element 5: [0187] the arms 2 a″′, in an extended condition, each form a kind of rectangle (in a side view) with rounded edges, [0188] the arms 2 a°, in an extended condition, each form a kind of semicircle (in a side view), [0189] the arms 2 a*, in an extended condition, each form a kind of isosceles triangle (in a side view), [0190] the arms 2 a{circumflex over ( )}, in an extended condition, each form a kind of semi-arrow (in a side view) with rounded edges.

[0191] It should be noted, moreover, that each extractable arm 2 a, 2 a″, 2 a′″, 2 a°, 2 a* and 2 a{circumflex over ( )} is arched (even if it does not develop according an actual arc of circumference except for the arms 2 a°) and extends substantially between said inner tubular body (4b) and said free end (5 a) of said rod-like element (5).

[0192] Even if two arms are shown in the examples of these variants, three, four or more arms can be envisaged, similar to the arms 2 a described above.

[0193] With reference to FIGS. 11-21, which show a preferred embodiment, it should be noted that, analogously to the conductors 39 of the petals, each arm 2 a of the head 2 also extends into the body 4b as far as the handpiece by means of elongated spiral-shaped portions 29.

[0194] Each elongated portion is preferably integral with the respective arm 2 a and is produced in the same material, preferably conductive such as Nitinol or similar.

[0195] Inside the body 4b, more specifically in the space between this and the guidewire 5, each elongated portion 29 is electrically isolated from the others, so that possible electric signals can be revealed (or transmitted) by the arms 2 a independently of each other.

[0196] In the enclosed preferred embodiment, moreover, additional second conductors 28 are envisaged for the positioning head, with advantages similar to those described above for the first additional conductors 38 (relating to the eddy currents).

[0197] These additional conductors 28 develop on a helix having the same pitch and the same diameter with respect to the elongated portions 29, and are interspersed with the latter, so that each elongated portion 29 of an arm 2 a is adjacent, at the two opposite sides, to two branches of the same—or different—additional conductor(s) 28.

[0198] In short, the effects relating to the reduction in the phenomena of eddy currents are thus reduced or even cancelled.

[0199] The additional conductors 28 are preferably made of copper, preferably shaped like U-folded wires inside the body 4b (or, alternatively, preferably all or part of them are electrically connected to each other), between this and the guidewire, analogously to the additional conductors 38 described above.

[0200] In the ablation apparatus, the above-mentioned additional dissipative conductors 28, 38 are preferably electrically connected to ground.

[0201] The objectives indicated above have therefore been achieved.